Refrigerating method and apparatus



Sept. 6, 1932. E. KINDERMANN K 1,875,875

REFRIGERATING METHOD AND APPARATUS u Filed March 21, 1929 3 Sheets-Sheet l :Ey @Gym agi-Fern @ys Sept. 6, 1932. E. KINDERMANN REFRIGERATING METHOD AND APPARATUS Filed March 21, 1929 5 Sheets-Sheet 2 mor/7696 Sept. 6, 1932- E. KINDERMANN 1,875,875

REFRIGERATING METHOD AND APPARATUS Filed March 21, 1929 5 Sheets-Sheet 3 Patented Sept. 6, 1932l UNITED STATESI PATENT OFFICE ERICH KINDERMANN, 0F BERLIN-REINICKENDORF-WEST, GERMANY, .Ag-SIGNOR TO DEUTSCHE GASGL'HLICHT-AUER-GESELLSCHAFT MIT 'IBESCHRANKTER HAFTUNG, 0F BERLIN, GERMANY, A CORPORATION 'OF GERMANY REFRIGERATING METHOD AND APPARATUS Application led March 21, 1929, Serial No.

Absorption refrigerating machinesworliing periodically with mixtures of liquid 'wlll require a device for the return of the re's1due of the solvent from the refrigerator to the absorption device. -It is not possible to construct the evaporator as a pot-like liquid collector without the use of mechanical closing members, and in such collectors the liquid of greater specific gravity will not flow ofi' at once. The return of the residue is particularly difcult, if the said residue of the solvent forms a constant mixture with the freshly admitted condensate owing to physical or chemical action, and thus the removal of the residue, if it is eected' only after a fresh admission of condensate, will be possible only by continuous dilution; With stationary machines it is necessary to remove the residue after the fresh admission of condensate, since mechanical closing elements cannot be employed with these household appliances.

The methods known up to the present for the automatical return only consider special cases and do not adapt themselves to the operation of absorption machines, causing trouble which will be different with every special type. Decisive for the manner of the return is the position of the evaporator in respect of the generator-absorber; the evaporator may be placed at a higher or lower level than the generator-absorber. In order to render automatical the operation of stationary aborption plants or machines, the heating or cooling medium is controlled either by time or in dependency on the operating temperatures prevailing at each particular moment. As however the temperature of the cooling medium and in consequence the pressure of condensation will never remain constant, the quantities of cooling medium forced out within'a definite period or range of temperature respectively will vary up to 50 per cent. As it is not possible to adjust the controlling means each time in conformity with the prevailing temperatures of the'cooling agent, it was necessary to design the evaporator for the smallest quantity of condensate and to return the excess of liquid during the return step unused to the generator-absorber. As the evaporator was mostly designed as a unitary, generally 348,743, and in Germany March 26, 1928.

cylindrical vessel, it was also necessary to remove the solvent according to its occurrence, and this problem was considered as solved, if the evaporator was emptied each time up to a certain level. These devices refused to work however, when the evaporator was completely filled up by solution. Even with a standard charge corresponding to the capacity of the evaporator there Will still occur losses in refrigerant during the return, since the solvent will have become concentrated again. In the case of an evaporator placed at a lower level than the generatorabsorber there was the danger that in the event of trouble with the cut-off| device for the heating medium either the heating coil was exposed if the contents of the evaporator were too large, or in the reversed instance the condenser was filled with condensate, which gave rise to inadmissible increase of pressure beyond the safety limit. v

The present invention relates to a method and apparatus for the return of the solvent in a safe manner without any losses thereof. For this purpose the admission is effected during the period of condensation and only such quantities of solvent are returned to the generator-absorber as have given olf excess refrigerant while producing cold. Accordlng to this method the simple evaporatmg vessel is dispensed with and is substituted by a system of individual evaporators, whose aggregate capacity is as large as, or larger than, the maximum quantity of refrigerant forced out.

The evaporating chambers of the individual evaporators are in open connection, and the liquid chambers are connected by means of circulation pipes, since they are charged with condensate not simultaneously but in succession in order to be able to remove the solvent, which in this manner is transferred or conveyed to the last individual evaporator during the charging operation. When l the Whole system is filled the liquids will be til generator-absorber is effected in various ways according tothe present invention. As the available space in the system corresponds to the maximum quantity of condensate, it is obvious that in the case of relatively high condenser pressure the system will b e filled only partly and considerable quantities of solvent will collect therein. rIhe spacing or separation-of the individual evaporators affords a safeguard against the evaporation of the pure refrigerant being aflected by injurious factors such as transfer of heat etc. The restriction of the heat transmitting connections also admits of the refrigerant which is mixed with the solvent during the charging, being evaporated again completely, in which case, as is well-known, the solutions possess different temperatures determined by the absorber pressure according to the concentra-tion of said solutions.

The solution discharged from the last individual evaporator, according to the present invention, can be conveyed to the generatorabsorber in various ways. lf the evaporator is at a higher level than the generator-absorber, no special pump or other transferring device is necessary and the solvent is allowed to pass into the generator-absorber by providing a suiiicient head. If the evaporator is placed at a lower level than the generatorabsorber, the supply according to the present invention is effected by means of the pumping effect of rising gas bubbles, corresponding to the evaporation proceedings in vertical heating tubes or to the operation of an air-lift.

The following methods may be employed here:

In the first instance the solution passes from the evaporator to a vertically arranged pipe with narrow cross-section, said pipe being heated from outside whereby the solution will be further relieved of gas and through the action of the risinggas bubbles in the various liquid containers it is lifted to the level of the generator-absorber. I-Ieating can be effected leither by means of an additional source of heat or through the hot solution from the boiler or generator absorber.

In the second case the solution enters in the same manner as described before into a vertically arranged pipe of narrow crosssection, into which pipe the vapours of the refrigerant expelled from the solution to the boiler or generator-absorber are passed, and during their upward flow to the condenser they will effect-the conveyance of the solution in the same manner as referred to above.

The subject matter of the invention is illustrated by way of example in the accompanying drawings in which Figure 1 shows the system with helical separate evaporators; the boiler or generator-absorber lying at a lower level.

Figure 2 shows a similar system with cylindrical separate evaporators.

. Figure 3 shows a system in which the boiler or generator-absorber lies at a higher level than the helical separate evaporators and conveying by heating from outside.

Figure 1- shows the same as Figure 3, but with conveying by the vapor to be condensed.

Figures 1 and 2 show a system in which separate evaporators are provided. Here the discharge of the solvent is effected by means of an overflow owing to high fall by gravity. In Figure 53 the discharge is effected by heating the vapors of the refrigerant from outside. In Figures l and 2, l designates the system of separate evaporators, which latter are shown in Figure 2 as cylindrical containers a to g, while according to Figure l they possess the form of a horizontal helical pipe. The individual windings or coils a to g of this pipe form the separate evaporators and are connected to a pressure compensating pipe 4. by means of the pressure compensating nozzles 2 and 3. e wWhile the nozzles 3 of the windings Z) to g extend into the pipe l for a considerable distance, the nozzle 2 enters the winding a at an obtuse angle, so that the condensate entering through the pipe 12 of the condenser 16 can get into the evaporating system only by way of the nozzle 2. A return pipe 6 connects the last evaporator g or g respectively, with the generator-absorber 7.

rl'he vapors expelled from the solution of the generator-absorber 7 by means of the heating device 9 iow through the pipe l() into a receiver 11, in which any water carried along is separated mechanically and returned to the generator-absorber by way of the pipe 13. After having passed through the receiver the vapors will enter a rectifying device (not shown), in which the contents of solvent are reduced to a few per cent, in order to be liquefied in the condenser pipe 12, which in this instance passes through the Water reservoir 16. The condensate then passes through the pipe 4 and nozzle 2 into the evaporating system and flows in succession through the separate evaporators commencing at a or a respectively. As the separate evaporators communicate with each other, (in the case of Fig. 2, by means of pipe 17) the residue of the solution left in the separate evaporators is conveyed through the system during this charging, and at the termination of this process it will be found in the extreme case within the separate evaporators f and g or f and g respectively. The solution found in this case in the evaporator g or g formed during the preceding cooling process the charge of the separate evaporator f or f and at that time it is freed to a great extent from the cooling medium, so that it is rendered useless for any fresh cooling process and for that reason it may be verator-absorber.

removed.' The outlets of the connecting pipes 17 are located at a higher level than theirinlets, and at about the same level with the outlet of the evaporator system to the gen- With this arrangement, a simultaneous emptying of all the evaporator vessels a to g will take place, by a sort of Siphon action, whenever there is a discharge of the contents of the last vessel, g', into the connecting pipe 6 which leads to the generator-absorber 7. According to Figure 3 the return to the generator-absorber is effected by the conveying means 6', 8 and 5. With`n the conveying pipe 6 the liquid willcommunicate with that contained in the evaporator g, that is to say the level of the4 liquid is so high that the latter can be heated by the hot solution from the generator-absorber passing through the circulating device and 5. Through such heating refrigerant 1s expelled in the state of vapor, which latter will carry the liquid up to the separator 14 if the generation of steam is sufficiently strong and the conveying pipe possesses a suciently small cross-section. The vapors could be conducted from said separator 14 directly to the condenser, but this is not intended in the present instance, and provision is made for the vapors and solution to pass together through the pipe 15 to the generator-absorber.

Figure 4 illustrates the same evaporating system, however in this instance the conveying means, are altered in conformity with the method observed. The solution flows from the last separate evaporator g through the pipe 6 to the liquid separator 14. The steam, carrying the solvent through the conveying pipe 6 to the liquid separator 14, comes from the generator-absorber 7 passes through the receiver and rectifier 11 and Hows through the pipe 18 into the conveying pipe 6 and thence 'to the separator 14 and' finally into the condenser 16. The solution remaining in the separator 14 passes to the generatorabsorber through a pipe 15.

In the'event of the controlling arrangement of the heating device becoming inoperative so that heating is continued longer than intended merely pure condensate will enter the conveying device. It is obvious that the condensate is conveyed in the same manner as the solution and in this case and at constant pressure in the condenser the following harmless condition of equilibrium will occur:

Admission of heat to the generator-absorber, expulsion of steam, liquefaction of the latter and entry into the evaporator. Discharge of the same quantity of liquid into the ,conveying device and conveyance of said liquid to the generator-absorber and evaporating it therein by removing from it the heat, that is to say the pressure, temperature and concentration of the poor solution in the generatorabsorber will remain constant.

I claim:

1. In the method of refrigeration which involves the heating of a liquid solvent for the refrigerant, in a generator-absorber, and the condensation of the liberated refrigerant, alternating with evaporation of such condensed refrigerant,the,step which consists in returning said solvent from the condenser through the evaporator to the generatorabsorber during the period of heating the generator-absorber and of condensing the refrigerant.

2. A method according to claim 1, in which the solvent is returned to the generator-absorber by gravity.

3. A method according to claim 1, in which the solvent is returned to the generator-absorber by the lifting action of gas bubbles.

4. A method according to claim' 1, in which the solvent is returned to the generator-absorber by the lifting action of gas bubbles produced by heating the returning stream of solvent externally.

5. A method according to claim 1, in which the solvent is returned to the generator-absorber by the lifting action of gas bubbles produced by heatinfr the returning stream of solvent externally 2by means of hot liquid from the generator-absorber.

6. A method according to claim 1, in which the solvent is returned to the generator-absorber by the lifting action of gas bubbles introduced into the returning stream of solvent.

7. A method according to claim 1, in which the solvent is returned to the generator-absorber by the lifting action of gas bubbles introduced into the returning stream of solvent, from the gaseous stream of refrigerant passing from the generator-absorber to the condensation.

8. An absorption refrigerating apparatus comprising a generator-absorber having an inlet and an outlet, a condenser whose inlet is connected with the outlet of the generatorabsorber, and evaporating means having an inlet connected with the outlet of the condenser and an outlet connected with the inlet of the generator-absorber, said means consisting of a plurality of separate evaporators each having an upper space for gas and a lower space for liquid, the gas spaces of all of said evaporators being in permanent communication with each other, while the liquid spaces of the several evaporators normally hold separate bodies of liquid but are connected in series to permit successive passage of liquid from one evaporator to the next.

9. An apparatus according to claim 8, in which the gas spaces of the several evaporators are connected to the condenser by means of a pressure-compensating pipe common to all of them.

10. An apparatus according'to claim 8, in which the gas spaces of the several evaporators are connected to the condenser by means IDO of a pressure-compensatin pipe common to all of them and in which t e first evaporator. of the series has its gas space connected with said pipe by a port ocated at the bottom of '5 the said pipe, while the other evaporators communicate with said pipe at points above its bottom.

11. An apparatus according to claim 8, in which the aggregate capacity of the several evaporators is at least equal to the maximum quantity of refrigerant liberated.

12. An apparatus according to claim 8, in which the several evaporators are constituted by coils of a substantially horizontal helical pipe. 1

13. An apparatus according to claim 8, in which the several evaporators consist of separate containers, the lower portion of each container having a connection for conveying 40 liquid from such container to the next.

14. An apparatus according to claim 8, in which the outlet of the last evaporator is at a higher level than the generator-absorber, so that liquid may pass from said outlet to the absorber by gravity.

15. An apparatus according to claim 8, in which the generator-absorber is at a higher level than the outlet of the last evaporator, and in which means are provided for causing gas bubbles to rise in the liquid on its way from such outlet to the generator-absorber and to assist the upward-motion of this liquid.

16. An apparatus according to claim 8, in which the generator-absorber is. at a higher level than the outlet of the last evaporator, and in which means are provided for heating the liquid on its way from such outlet to the generator-absorber, so as to produce in such liquid, gas bubbles which will assist the upward motion of the liquid.

17. An apparatus according to claim 8, in which the generator-absorber is at a higher level than the outlet of the last evaporator, and in which a pipe is provided for conveying liquid from such outlet upwardly to the generator-absorber, and in which a conduit connected with the generator-absorber conveys hot liquid from the generator-absorber to the vicinity of said pipe, to heat the rising column of liquid and produce gas bubbles therein.

18. An apparatus according to claim 8, in which the generator-absorber is at a higher level than the outlet of the last evaporator,

and in which. a pipe is provided for conveying liquid from such outlet upwardly to the generator-absorber, and in which a connection is provided for leading gases to the lower portion of said pipe, `from a point located between the outlet of the generator-absorber and the inlet of the condenser.

In testimon whereof I aiiix my signature.

ERICH KINDERMANN. 

